Onshore oil drilling usually involves the production of a byproduct in the form of wastewater. Water is usually located above the oil layer in the ground. Water containing oil is often the first product of oil drilling. Treatment of such wastewater from onshore oil wells poses several challenges. Most commercial onshore processes, when ocean discharge is not available, include reducing the oil content in the water to approximately below 10 mg/liter, removing coarse particles and then injecting the received oilfield produced water via a deep aquifer injection. In some cases oilfield produced water cannot be used without further treatment due to excessive contamination and high salt levels. In such cases, a further reduction of pollutants and oil should be achieved and the water should be desalinated to meet stricter environmental regulations.
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